Yeah, I've heard the same thing too, but in all honesty I don't think so. I've had new clones in the stuff as well as popped seeds in it, nothing bad has happened in any case.
FFOF was the only thing i used for my plants, even new clones. i never really had any problems that i can remember. as long as u feed just plain water for the first few weeks, they take up only what they need
I've transplanted Newly rooted clones that were like two inches tall in FFOF....four different strains....one of them didn't grow for like two weeks...I'd almost given up on it, then it just spouted and filled out faster than other plants that were a couple weeks older, and on the older ones I waited for established roots before I transplanted. Thier all doing good but You can put newly rooted clones in FFOF.....You just over there makin fried weed bites or something J/K I've heard people say that, but I have never had a problem...but if you fed nuted water within a week or so..thats what did it.
I've also heard that some strains think Ocean Forest is too hot to clone or start from see with. But it worked for me with 3 of the 4 popped seeds I put straight in (bagseed so that one might have been a dud anyway)
Yeah, it must have been the strain... I've rooted some clones and they look great, and others you can tell are feeling the heat although I've never lost one because it was too hot. I also root tomato clones in FFOF perfectly